The present invention relates to stable bleaching tablets. More particularly, tablets comprising diperazelaic acid, or the like, as the active bleaching material together with agents which contribute to the shelf life, thermal stability and proper disintegration rate of the tablets are provided.
The most familiar method of bleaching fabrics to remove stains, especially in the context of a home laundering operation, is to add an oxidizing bleach directly to the laundering liquor. Liquid chlorine (as hypochlorite) solutions are usually employed, but granular peroxygen bleaches are also commercially available. The addition of a bleaching agent to a laundering bath in conjunction with a detergent has the distinct advantage of providing the desired bleaching action concurrently with fabric laundering.
The present invention relates to the use of peroxygen compounds, especially diperazelaic acid, to bleach fabrics in an aqueous bath. Peroxygen compounds offer considerable advantages as bleaches over the more common chlorine bleaches, since they are milder and do not undesirably interact with fabrics and dyes when properly used.
In spite of the inherent advantages of many peroxygen bleaches over chlorine bleaches, the peroxygen bleaches currently being marketed are not as effective as the chlorine bleaches. Other, more effective peroxygen bleaches are known but have not been made available to the consumer heretofore, since many of these more effective (from a bleaching standpoint) peroxygen bleaches suffer from a variety of problems which could not be tolerated in home usage. For example, some highly effective peroxygen bleaches are too flammable and pose safety problems; other peroxygen bleaches are quite expensive; a common problem with most peroxygen bleaches is their lack of stability on prolonged storage. Whatever the reason, the more highly effective peroxygen bleaches are not currently available for use in the home.
By the present invention it has been discovered that useful bleaches can be provided by tableting peroxygen compounds in the manner disclosed hereinafter. The tableted bleaches herein are stable, safe and effective and are specifically designed for home use in a typical fabric laundering situation.